I don't know the cause (haven't installed a Windows VMPro for maybe 5 years now), but back when I used to, you had to be aware even if installing to the D drive, the install process still needed a lot of free space the C drive (or wherever the Windows OS was) and some components (for example .NET components) still get installed on the C drive only.
Also, as our non-English speaking brethren have discovered, Avaya have gotten pretty poor at checking anything other than an English installation to the default location.
So why, unless you like the unnecessary pain of swimming uphill through Avaya support, do you need to install it to the D; drive? or can't install an IP Office Application server?
Stuck in a never ending cycle of file copying.